GLuint not being recognised

Did you include the OpenGL header in the header you're declaring the variable in? GLuint is defined in gl.h so you must include that.

On all operating systems except MacOS X it's

#include <GL/gl.h>

on MacOS X it is

#include <OpenGL/gl.h>

I think you should be using glew and include:

#include <GL/glew.h>

rather than:

#include <GL/gl.h>